Stable oxidizing bromine formulations, method of manufacture and uses thereof for biofouling control

ABSTRACT

Stable biocide formulations containing oxidizing bromine are provided for biofouling control in industrial water systems. The formulations contain at least one stable oxidizing bromine compound that is prepared from at least one oxidizing chemical reagent, at least one bromine source and at least one bromine or halogen stabilizer. The resulting products are a mixture of stable oxidizing bromine compounds that can be used as a biocide in an industrial water system.

FIELD OF THE INVENTION

The present invention relates to formulations used in biofouling controlin industrial water systems. More specifically, the present inventionrelates to methods of preparing stable oxidizing bromine formulationsand their use in biofouling control in industrial water systems.

BACKGROUND OF THE INVENTION

While elemental liquid bromine is an effective biocide, its lowsolubility (<4 g/100 g water), low boiling point (54.3° C.), high vaporpressure (214 mm Hg at 25° C.) and extreme corrosivity limit its use asa biocide in industrial applications. Another oxidizing brominecompound, bromate, has very little antimicrobial activity. Bromate isalso very toxic to mammals and is a suspected carcinogen. Nonoxidizinginorganic bromine compounds, such as bromide, have little or noantimicrobial activity.

A mixture of an aqueous bromine solution and a bromine stabilizer hasbeen used to generate stable oxidizing bromine compounds for use as abiocide. An unstabilized aqueous bromine solution is very acidic,unstable and emits very pungent bromine fumes. The concentration ofstabilized hypobromite solution that can be made from liquid bromine,however, has been limited due to the low solubility of bromine in water.

It has also been suggested that, in addition to a bromine stabilizer, anoxidizer, such as hypochlorite, be added to activate the bromide tohypobromite. After the completion of the conversion of bromide tohypobromite, the hypobromite is stabilized by the addition of a halogenstabilizer, such as sulfamate. While this is an improved process with ahigher level of oxidizing halogen content (around 14% as Br₂), thisprocess still requires the separate step of synthesizing sodiumhypobromite (NaOBr) as a bromine source. NaOBr is known to be veryunstable and will rapidly disproportionate to bromide and bromate, bothof which have little or no antimicrobial activity. In addition, becausesodium hypochlorite (NaOCl) is used as an activation agent, theconcentration of stabilized product is limited by the availableconcentration of NaOCl.

Also known are methods of generating bromine for on-site use. Suchprocesses involve electrolytically converting bromate into activebromine compounds such as bromine, hypobromous acid, hypobromite ion andhydrogen tribromide under acidic conditions. However, because the aboveprocess generates bromine for on-site use, methods or measures foroptimizing bromine stabilization are not addressed.

Therefore, methods of generating higher concentrations of stableoxidizing bromine formulations in a safer manner are needed.

SUMMARY OF THE INVENTION

The present invention satisfies the aforementioned needs by providing amethod of generating a stable oxidizing bromine compound which includesthe steps of mixing an alkali or alkaline earth metal bromide and analkali or alkaline earth metal bromate in water to provide an aqueoussolution, cooling the solution to a temperature of less than 25° C.,preferably less than 20° C. and more preferably less than 10° C., andthereafter adding a halogen stabilizer to the solution, the halogenstabilizer being selected from the group consisting of R--NH₂,R--NH--R¹, R--SO₂ --NH₂, R--SO₂ --NHR¹, R--CO--NH₂, R--CO--NH--R¹ andR--CO--NH--CO--R¹ wherein R is a hydroxy group, an alkyl group or anaromatic group and R¹ is an alkyl group or an aromatic group. Preferredhalogen stabilizers include urea, thiourea, creatinine, cyanuric acids,alkyl hydantoins, mono or diethanolamine, organic sulfonamides, biuret,sulfamic acid, organic sulfamates and melamine. Sulfamic acid is themost preferred halogen stabilizer.

In an embodiment, the halogen stabilizer is added to the solution in amolar amount approximately equal to the combined molar amount of alkalior alkaline earth metal bromide and alkali or alkaline earth metalbromate.

In an embodiment, the step of adding the halogen stabilizer results inthe solution having a pH of less than 2.

In an embodiment, the method comprises agitating the solution for a timeperiod of greater than 5 minutes after the step of adding the halogenstabilizer.

In an embodiment, the method comprises adjusting the solution to a pH ofgreater than 13 through the addition of alkali or alkaline earth metalhydroxide after the step of adding the halogen stabilizer.

In an embodiment, the step of mixing the alkali or alkaline earth metalbromide and alkali or alkaline earth metal bromate further comprisesmixing the alkali or alkaline earth metal bromide and alkali or alkalineearth metal bromate in a molar ratio of alkali or alkaline earth metalbromide:bromate of about 2:1.

In an embodiment, the method of the present invention provides a stableoxidizing bromine compound which includes the steps of mixing about 2moles of alkali or alkaline earth metal bromide and about 1 mole ofalkali or alkaline earth metal bromate in water to provide an aqueoussolution, followed by the step of cooling the solution to a temperatureof less than 10° C., followed by the step of adding an acidic halogenstabilizer to the solution to lower the pH of the solution to less than2, the acidic halogen stabilizer being selected from the groupconsisting of R--NH₂, R--NH--R¹, R--SO₂ --NH₂, R--SO₂ --NHR¹,R--CO--NH₂, R--CO--NH--R¹ and R--CO--NH--CO--R¹ wherein R is a hydroxygroup, an alkyl group or an aromatic group and R¹ is an alkyl group oran aromatic group. Preferred halogen stabilizers include urea, thiourea,creatinine, cyanuric acids, alkyl hydantoins, mono or di ethanolamine,organic sulfonamides, biuret, sulfamic acid, organic sulfamates andmelamine. The acidic halogen stabilizer is added to the solution in amolar amount approximately equal to a combined molar amount of alkali oralkaline earth metal bromide and alkali or alkaline earth metal bromate,followed by the step of agitating the solution for a time period ofgreater than 5 minutes, followed by the step of adding an alkali oralkaline earth metal hydroxide to the solution to increase the pH of thesolution to a level greater than 13.

In an embodiment, the method of the present invention provides a methodof preparing a stable oxidizing bromine compound which includes thesteps of preparing a caustic solution comprising a halogen stabilizer,water and an alkali or alkaline earth metal hydroxide, adding bromine tothe solution while agitating the solution and cooling the solution.

In an embodiment, the halogen stabilizer is selected from the groupconsisting of R--NH₂, R--NH--R¹, R--SO₂ --NH₂, R--SO₂ --NHR¹,R--CO--NH₂, R--CO--NH--R¹ and R--CO--NH--CO--R¹ wherein R is a hydroxygroup, an alkyl group or an aromatic group and R¹ is an alkyl group oran aromatic group. Preferred halogen stabilizers include urea, thiourea,creatinine, cyanuric acids, alkyl hydantoins, mono or di ethanolamine,organic sulfonamides, biuret, sulfamic acid, organic sulfamates andmelamine.

In an embodiment, the caustic solution has a pH greater than 13 afterthe addition of bromine.

In an embodiment, the step of adding bromine is further characterized asadding bromine in a molar amount approximately equal to the molar amountof halogen stabilizer and approximately equal to one-half of the molaramount of alkali or alkaline earth metal hydroxide.

In an embodiment, the solution is cooled to a temperature of less than25° C.

In an embodiment, the step of adding bromine is performed withoutexposing the bromine to air.

In an embodiment, an alkali or alkaline earth metal hydroxide is addedto the solution after the addition of bromine to increase the pH of thesolution above 13.

In an embodiment, the method of the present invention provides a methodof preparing a stable oxidizing bromine compound in an aqueous solutionwhich includes the steps of dissolving an alkali or alkaline earth metalbromate salt in water to form a solution, followed by the step of addinga halogen stabilizer to the solution, the halogen stabilizer beingselected from the group consisting of R--NH₂, R--NH--R¹, R--SO₂ --NH₂,R--SO₂ --NHR¹, R--CO--NH₂, R--CO--NH--R¹ and R--CO--NH--CO--R¹ wherein Ris a hydroxy group, an alkyl group or an aromatic group and R¹ is analkyl group or an aromatic group. Preferred halogen stabilizers includeurea, thiourea, creatinine, cyanuric acids, alkyl hydantoins, mono or diethanolamine, organic sulfonamides, biuret, sulfamic acid, organicsulfamates and melamine. Following the addition of the halogenstabilizer, bromine is added to the solution.

In an embodiment, a step of cooling the solution to a temperature ofless than 25° C., preferably less than 15° C. and more preferably lessthan 10° C., is performed simultaneously with the step of adding thebromine to the solution.

In an embodiment, the present invention provides an aqueous biocidesolution containing a stable oxidizing bromine formulation. The solutioncomprises at least one oxidizing bromine compound selected from thegroup consisting of ⁻ SO₃ NHBr and ⁻ SO₃ NBr₂ when sulfamate is used asthe bromine stabilizer and a base in an amount sufficient to raise thepH of the solution to a level greater than 13.

In an embodiment, the base in the solution is an alkali or alkalineearth metal hydroxide.

It is therefore an advantage of the present invention to generate astable oxidizing bromine solution using liquid bromine in a safe andefficient manner whereby no bromine fumes are generated.

It is another advantage of the present invention to generate a higherconcentration of stabilized hypobromite without the need for a separatestep for hypobromite generation.

Another advantage of the present invention is that it provides a methodfor generating water soluble solid stable oxidizing bromine compounds.

Still another advantage of the present invention is that it provides amethod for generating stable oxidizing bromine compounds withoutunwanted by-products such as high levels of bromate.

Still another advantage of the present invention is that the method ofthe present invention does not generate chloride and therefore themethod of the present invention provides stable oxidizing bromineformulations that are less corrosive.

Yet another advantage of the present invention is that it providesstable oxidizing bromine compounds that are safer to transport and thatare non-acidic.

Yet another advantage of the present invention is that it generatesstable oxidizing bromine compounds for biofouling control in industrialwater systems that are more compatible with other water treatmentchemicals than unstabilized oxidizing bromine compounds.

The industrial water systems include cooling water systems, coolingponds, reservoirs, sweetwater applications, decorative fountains,pasteurizers, evaporative condensers, hydrostatic sterilizers andretorts, gas scrubber systems and air washer systems.

Another advantage of the present invention is that it provides animproved method of biofouling control in pulp and paper processingsystems.

Another advantage of the present invention is that it provides animproved method of biofouling control occurring on the surfaces ofequipment in contact with produced oil field waters.

Another advantage of the present invention is that it provides animproved method of biofouling control in a food processing system.

Yet another advantage of the present invention is that it providesimproved biofouling control in a beverage processing system.

Still another advantage of the present invention is that it providesimproved biofouling control in a recreational water system.

Another advantage of the present invention is that it provides animproved method of disinfecting a hard surface.

Another advantage of the present invention is that it provides animproved bleaching method for the laundering of soiled garments and forthe manufacture of cellulosic materials.

And, another advantage of the present invention is that it provides animproved method of washing food items, such as fruit and other fooditems.

Other objects and advantages of the present invention will be apparentupon a review of the following detailed description and appended claims.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a plurality of formulations and methodsfor generating a wide concentration of stable oxidizing brominecompounds for biofouling control in cooling water and other industrialsystems.

In an embodiment, the strategy employed by the present inventionutilizes a mixture of alkali or alkaline earth metal bromide and alkalior alkaline earth metal bromate in water as the bromine source. Bromatealso serves as an oxidizing agent. The molar ratio of bromide to bromateis optimally 2:1. The solution is then cooled to a temperaturepreferably of less than 25° C. and even more preferably of less than 10°C. An acidic stabilizer or acidic stabilizing solution, such as sulfamicacid, is then added to the solution to lower the pH of the solution toless than 2. Additional stabilizer is then added to achieve equal molaramounts relative to bromine for optimal stabilization. Without beinglimited by theory, the following reactions are believed to occur:

    HO-SO.sub.2 -NH.sub.2 →H.sup.+ +.sup.- O-SO.sub.2 -NH.sub.2(1)

    2Br.sup.- +BrO.sub.3.sup.- +3H.sup.+ →3HBrO         (2)

    HBrO+.sup.- O-SO.sub.2 -NH.sub.2 →.sup.- O-SO.sub.2 -NH-Br, .sup.- O-SO.sub.2 -NBr.sub.2, and other stable oxidizing bromine compounds(3)

Since bromide, bromate and sulfamate co-exist in the resulting solution,reaction (1) to reaction (3) occurs sequentially with respect to eachother. Without being limited by theory, the existence of an oxidizingbromine stabilizer and correct bromide to bromate ratio are believed toprevent the formation of bromine according to the following reaction:

    5NaBr+NaBrO.sub.3 +6H.sup.+ →3Br.sub.2 +6Na.sup.+ +3 H.sub.2 O(4)

If reaction (4) were to happen instead of reaction (2), half of the rawbromine source would convert back to non-biocidal and non-oxidizingbromide according to reaction (5):

    Br.sub.2 +H.sub.2 O→HBrO+HBr                        (5)

However, an analysis of products prepared in accordance with the presentinvention confirms that the reaction yield is higher than 50%. In fact,more than 80% of the bromine source was converted to oxidized bromineforms. Accordingly, the reaction yield of at least 80% was achieved.

The reaction time for reactions 1-3 at a pH of less than 2 ranges from 5to 10 minutes with good agitation. If the product is not going to beused immediately, a strong base, such as NaOH, is added to raise theproduct pH to a level greater than 13 making the product thermallystable. During the pH adjustment, temperature control is importantbecause the temperature increase by the heat generated from theacid-base reaction can cause the product to decompose. Accordingly,cooling may be necessary.

The product made with the above process has good thermostability and ahigh total available halogen concentration, as high as 34% as Br₂.

EXAMPLES

The following examples are intended to be illustrative of the presentinvention and to teach one of ordinary skill how to make and use theinvention. These examples are not intended to limit the invention or itsprotection in any way.

Example I

By way of an example, synthesis of a stable oxidizing bromine product inaccordance with the above-described method is carried out by mixing 21.2grams of NaBrO₃, 32.8 grams of NaBr and 100 grams of water, cooling thesolution to 3° C., adding 48 grams of sulfamic acid to the solution andagitating the solution for 10 minutes. Then, 48 grams of 50% aqueousNaOH is added slowly to the solution while controlling the solutiontemperature to a range between 4° C. and 14° C. The resulting productwas a golden yellow solution with a pH of 13.77 and available halogenconcentration of 25.1% as Br₂. In this example, the theoretical Br₂ % is29.9 if all of the bromine sources (bromide and bromate) were to convertto stable oxidizing bromines. Therefore, the yield is about 84%.

Example II

By way of another example, synthesis of stable oxidizing bromineformulations in accordance with the above-described method is carriedout by mixing 21.2 grams of NaBrO₃, 32.8 grams of NaBr and 100 grams ofwater in a reactor, cooling the solution to 3° C., adding 44 grams ofsulfamic acid to the solution and agitating the solution for 10 minutes,slowly adding 43 grams of 50% aqueous NaOH while controlling the reactortemperature between 3° C. and 14° C. The resulting product was a goldenyellow solution with a pH of 14.11 and available halogen concentrationof 27.7% as Br₂. In this example, the theoretical Br₂ % is 31.2 if allof the bromine sources (bromide and bromate) are converted into stableoxidizing bromines. Therefore, the product yield is about 88.8%.

In another embodiment, liquid bromine is used as both oxidizer andbromine source. Sulfamate or other nitrogen base compounds are used asstabilizers. In addition, an adequate amount of alkali or alkaline earthmetal hydroxide is required to maintain product pH. Formulationtemperature is also extremely critical in insuring the formation ofstable oxidizing bromines. Without adequate pH and temperature control,the heat generated by the exothermic reaction will cause rapiddecomposition of the oxidizing species.

The process of making high concentration stable oxidizing bromineformulations consists of two steps. In the first step, a causticstabilizing solution is prepared by mixing sulfamic acid, water andalkali or alkaline metal hydroxides (preferably NaOH, Mg(OH)₂ or otherhydroxides). The pH of the alkali or alkaline earth metal sulfamatesolution is higher than 14. Excess hydroxides are purposely added toneutralize the acids generated by the subsequent bromination step and tomaintain a high pH (preferably greater than 13) in the finished product.The preferred molar ratio of sulfamate to liquid bromine is 1:1. Thepreferred molar ratio of hydroxide to liquid bromine is 2.2:1. Thestabilizer solution can also be obtained by dissolving alkali oralkaline metal sulfamate in water and adding an appropriate amount ofhydroxide.

The process is normally carried out in a jacketed glass reactor equippedwith a proper mixing device. A cooling system for the reactor should beset up so that the reactor temperature can be controlled at an optimalrange. An excessively high reaction temperature during the brominationstep will accelerate sulfamate hydrolysis and cause decomposition of thedesired product.

The second step of the process is to slowly add liquid bromine into thestabilizer solution under good agitation. Bromine is preferably addeddirectly into the stabilizer solution through a Teflon® tube to preventelemental bromine exposure to air. The addition rate is controlled sothat the reaction temperature is preferably below 25° C. The higher thereaction temperature, the lower the product yield. If the reactiontemperature gets over 35° C., sulfamate will start hydrolyzing intosulfate and ammonium. The resulting ammonium will react with and consumehypobromite and produce nitrogen gas which can be observed as vigorousfoaming. With proper addition rates of liquid bromine, the liquidbromine will react instantaneously and will be stabilized. The processdoes not produce detectable bromine fumes.

The product made with the above-described process was found to includeno detectable bromate (less than 50 ppm with ion chromatographyanalysis); no detectable product concentration change was observedduring a 2 month storage period at room temperature. For a 16.2% (asBr₂) product, the product has a half life of 74.5 days at 57° C.

Example III

By way of an example, synthesis of a stable oxidizing bromine productusing the above-described method is achieved by mixing 52.16 grams ofsulfamic acid, 42.0 grams of water and 128.0 grams of 50% aqueous NaOHin a 500 ml three-neck glass reactor. The mixture is cooled to atemperature of about 3° C. under constant agitation and refrigerated ina water bath. 82.5 grams of liquid bromine (99.8% Br₂) is slowly addedto the solution and the reaction temperature is controlled andmaintained below 10° C. The resulting solution has a pH of 12.5. Thesolution pH was increased to a level greater than 13 by adding 3.0 gramsof 50% NaOH. The bromine content in the resulting solution was 26.2% asBr₂ while a theoretical content if 100% conversion is achieved is 27.0%as Br₂.

After overnight storage at room temperature (21° C.), the formation oflarge amounts of crystals was observed in the solution. Using a 0.45 μmfilter to separate the crystal from the liquid, followed by dehydrationof the crystals under vacuum overnight, 46.8% as Br₂ was detected in thesolid product while 18.7% of bromine content as Br₂ remained in theliquid. The solid product was found to be extremely water soluble.Accordingly, the present invention provides a solid stable oxidizingbromine product which is water soluble.

The solid product obtained in the above example has a very highconcentration of stable oxidizing bromine compounds. The remainingcontent is believed to be water, excess NaOH and NaBr.

Other hybrid methods can be used to generate stable oxidizing brominecompounds. One such method consists of using bromate salt as an oxidizerand bromine source, liquid bromine as an oxidizer, bromine source andacidic compound and sulfamate or another suitable halogen stabilizer asthe bromine stabilizer. The reaction mechanism would be as follows:

    Br.sub.2 +H.sub.2 O→2H.sup.+ +Br.sup.- +OBr.sup.-   (6)

    BrO.sub.3.sup.- +2Br.sup.- +H.sup.+ →3OBr.sup.-     (7)

    OBr.sup.- +Stabilizer→Stable oxidizing bromines     (8)

The process can be carried out by dissolving bromate salt and water,adding sulfamate or other stabilizer to the solution, slowly addingliquid bromine, adjusting the pH to a level greater than 13 by addingNaOH, if the resulting product is to be stored for a long period oftime. The process should be conducted at a temperature less than 25° C.,especially during the addition of liquid bromine.

In an embodiment, the stable oxidizing bromine compound of the presentinvention can be used to provide improved biofouling control inindustrial water systems, pulp and paper processing systems, food andbeverage processing systems and recreational water systems. The stableoxidizing bromine compound of the present invention can also be used asa bleaching agent and to disinfect a hard surface. By way of exampleonly, the present invention may be added to an aqueous media used totransport food through various processing systems and also to disinfectprocess equipment and waste water streams.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present invention andwithout diminishing its attendant advantages. It is therefore intendedthat such changes and modifications be covered by the appended claims.

What is claimed is:
 1. A method of generating a stable oxidizing brominecompound, the method comprising the following steps:mixing an alkali oralkaline earth metal bromide and an alkali or alkaline earth metalbromate in water to provide an aqueous solution, cooling the solution toa temperature less than 25° C., and adding a halogen stabilizer to thesolution, the halogen stabilizer being selected from the groupconsisting of R--NH₂, R--NH--R¹, R--SO₂ --NH₂, R--SO₂ --NHR¹,R--CO--NH₂, R--CO--NH--R¹ and R--CO--NH--CO--R¹ wherein R is a hydroxygroup, an alkyl group or an aromatic group and R¹ is an alkyl group oran aromatic group.
 2. The method of claim 1 wherein the halogenstabilizer is selected from the group consisting of urea, thiourea,creatinine, cyanuric acids, alkyl hydantoins, monoethanolamine,diethanolamine, organic sulfonamides, biuret, sulfamic acid, organicsulfamates and melamine.
 3. The method of claim 1 wherein the halogenstabilizer is added in a molar amount approximately equal to a combinedmolar amount of alkali or alkaline earth metal bromide and alkali oralkaline earth metal bromate.
 4. The method of claim 1 wherein thehalogen stabilizer is sulfamic acid.
 5. The method of claim 1 whereinthe step of adding the halogen stabilizer results in the solution havinga pH of less than
 2. 6. The method of claim 1 further comprising thefollowing step after the step of adding the halogen stabilizer:agitatingthe solution for a time period greater than 5 minutes.
 7. The method ofclaim 1 further comprising the following step after the step of addingthe halogen stabilizer:adjusting the solution to a pH of greater than13.
 8. The method of claim 1 wherein the step of mixing the alkali oralkaline earth metal bromide and alkali or alkaline earth metal bromatefurther comprising mixing the alkali or alkaline earth metal bromide andthe alkali or alkaline earth metal bromate in a molar ratio of alkali oralkaline earth metal bromide:bromate of about 2:1.
 9. A method ofgenerating a stable oxidizing bromine compound, the method comprisingthe following steps:mixing about 2 moles of alkali or alkaline earthmetal bromide and about 1 mole of alkali or alkaline earth metal bromatein water to provide an aqueous solution, cooling the solution to atemperature of less than 10° C., adding an acidic halogen stabilizer tothe solution to lower the pH of the solution to less than 2, the acidichalogen stabilizer being selected from the group consisting of urea,thiourea, creatinine, cyanuric acids, alkyl hydantoins,monoethanolamine, diethanolamine, organic sulfonamides, biuret, sulfamicacid, organic sulfamates and melamine, the acidic halogen stabilizerbeing added in a molar amount approximately equal to a combined molaramount of alkali or alkaline earth metal bromide and alkali or alkalineearth metal bromate, agitating the solution for a time period greaterthan 5 minutes, and adding an alkali or alkaline earth metal hydroxideto the solution to increase the pH of the solution to greater than 13.10. A method of generating a stable oxidizing bromine compound, themethod comprising the following steps:preparing a caustic solutioncomprising a halogen stabilizer, water and an alkali or alkaline earthmetal hydroxide, the halogen stabilizer being selected from the groupconsisting of R--NH₂, R--NH--R¹, R--SO₂ --NH₂, R--SO₂ --NHR¹,R--CO--NH₂, R--CO--NH--R¹ and R--CO--NH--CO--R¹ wherein R is a hydroxygroup, an alkyl group or an aromatic group and R¹ is an alkyl group oran aromatic group, adding bromine to the solution while mixing thesolution, and cooling the solution.
 11. The method of claim 10 whereinthe halogen stabilizer is selected from the group consisting of urea,thiourea, creatinine, cyanuric acids, alkyl hydantoins,monoethanolamine, diethanolamine, organic sulfonamides, biuret, sulfamicacid, organic sulfamates and melamine.
 12. The method of claim 10wherein the caustic solution has a pH after the addition of bromine ofgreater than
 13. 13. The method of claim 10 wherein the step of addingbromine is further characterized as adding bromine in a molar amountapproximately equal to a molar amount of halogen stabilizer andapproximately one-half of a molar amount of alkali or alkaline earthmetal hydroxide.
 14. The method of claim 10 wherein the cooling step isfurther characterized as cooling the solution to a temperature of lessthan 25° C.
 15. The method of claim 10 wherein the step of addingbromine is performed without exposing the bromine to air.
 16. The methodof claim 10 further comprising the following step after the addition ofthe bromine:adding an alkali or alkaline earth metal hydroxide to thesolution to increase the pH of the solution above
 13. 17. A method ofgenerating a stable oxidizing bromine compound, the method comprisingthe following steps:preparing a caustic solution comprising a halogenstabilizer, water and an alkali or alkaline earth metal hydroxide, thehalogen stabilizer being selected from the group consisting of urea,thiourea, creatinine, cyanuric acids, alkyl hydantoins,monoethanolamine, diethanolamine, organic sulfonamides, biuret, sulfamicacid, organic sulfamates and melamine, adding bromine to the solution ina molar amount approximately equal to a molar amount of halogenstabilizer and approximately one-half of a molar amount of alkali oralkaline earth metal hydroxide and without exposing the bromine to air,mixing the solution, the solution having a pH after the mixing step ofgreater than 13, cooling the solution to a temperature of less than 25°C., and adding an alkali or alkaline earth metal hydroxide to thesolution to increase the pH of the solution above
 13. 18. A method ofgenerating a stable oxidizing bromine compound in an aqueous solution,the method comprising the following steps:dissolving an alkali oralkaline earth metal bromate salt in water to form a solution, adding ahalogen stabilizer to the solution, the halogen stabilizer beingselected from the group consisting of R--NH₂, R--NH--R¹, R--SO₂ --NH₂,R--SO₂ --NHR¹, R--CO--NH₂, R--CO--NH--R¹ and R--CO--NH--CO--R¹ wherein Ris a hydroxy group, an alkyl group or an aromatic group and R¹ is analkyl group or an aromatic group, and adding bromine to the solution.19. The method of claim 18 wherein the halogen stabilizer is selectedfrom the group consisting of urea, thiourea, creatinine, cyanuric acids,alkyl hydantoins, monoethanolamine, diethanolamine, organicsulfonamides, biuret, sulfamic acid, organic sulfamates and melamine.20. The method of claim 18 further comprising the following stepperformed simultaneously with the step of adding bromine:cooling thesolution to a temperature of less than 25° C.